1. Field
One or more embodiments of the present invention relates to a method, medium and apparatus for outputting a sound source signal by using a virtual speaker, and more particularly, to a method and apparatus for outputting a sound source signal in order to provide a personal sound zone which delivers a sound having no distortion in terms of sound quality to a user by removing a non-uniform radiation pattern generated from a speaker array system formed of a plurality of speakers.
2. Description of the Related Art
A speaker array combines a plurality of speakers and is used to control a direction in which sound is to be reproduced and to send a sound to a specific area. In order to control a sound to be in a target area or a target direction, an array including variety of sound source signals is needed. In general, a principle of delivering a sound which is known as directivity uses a phase difference of a variety of sound source signals and piles up the signals in order to increase the strength of the signal in a specific direction, thereby delivering the signals in a specific direction. Accordingly, phases of the sound source signals generated through the plurality of the speakers located according to a specific position are controlled so that such directivity can be realized. Such a directivity principle is used to focus a sound to a specific listener's position. An area where a sound field is formed due to focusing is called a personal sound zone.
Hereinafter, the term ‘sound source’ denotes a source in which a sound is radiated and means a separate speaker which forms a speaker array. The term ‘sound field’ is a virtual area formed by a sound radiated from a sound source and is used to denote an area to which a sound energy is affected. In addition, the term ‘sound pressure’ represents the amount by which sound energy is affected, by using a physical quantity of pressure.
Meanwhile, in outputting the sound source signals through the speaker array, a phenomenon occurs in that radiation properties are generated non-uniformly in the sound source signals radiated from each speaker in a position within a specific distance from the speaker array due to insufficient interference. This phenomenon occurs because a sound radiated from a variety of the speakers cannot form a desired sound field in a short distance of the speaker array due to insufficient interference from separate radiated sound source signals. This is called a near field effect. In addition, when a sound field radiated from the speaker array is represented as a visual pattern, such a near field effect is represented as a non-uniform radiation pattern.